(上海交通大學(xué) 材料科學(xué)與工程學(xué)院，上海 200240)
摘 要: 利用相場(chǎng)方法研究Ni2MnGa形狀記憶合金中不同連續(xù)拉應(yīng)力方向馬氏體孿晶變體的再取向動(dòng)力學(xué)。模擬結(jié)果表明：施加應(yīng)力方向決定體系演化的最終結(jié)構(gòu)和演化路徑，沿[100]和[110]方向施加應(yīng)力分別得到單變體和雙變體，而沿[111]方向施加應(yīng)力，體系依然保持為3種變體。計(jì)算了相應(yīng)的與界面動(dòng)力學(xué)因子和切變模量相關(guān)聯(lián)的孿晶化應(yīng)力，計(jì)算結(jié)果與實(shí)驗(yàn)結(jié)果接近。加載和卸載后2種變體和3種變體之間的組織轉(zhuǎn)化具有可逆性。
關(guān)鍵字: Ni2MnGa合金；馬氏體孿晶變體；再取向動(dòng)力學(xué)；孿晶化臨界應(yīng)力；相場(chǎng)模擬
（School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China）
Abstract:The kinetics of reorientation of martensitic twin variants under the continuous tensile stress along different directions in Ni2MnGa shape memory alloys was investigated by phase-field method. The simulated results reveal that the final morphology and the pathway of microstructural evolution depend on the stress-applied direction. The single variant and two variants can be obtained when the external stress is applied along [100] and [110] directions, respectively, while three variants still exist when the stress is applied along [111] direction. The corresponding twinning stress related to interfacial dynamic factor and shear modulus was calculated, which is close to the experimental measurements. The structural evolution between two variants and three variants has good reversibility during loading and unloading.
Key words: Ni2MnGa alloy; martensitic twin variants; reorientation kinetics; critical twinning stress; phase-field simulation
